L1 is Associated with Favorable Outcome in Neuroblastomas in Contrast to Adult Tumors

Background: Neuroblastoma is the most common solid tumor in childhood with unconventional clinical behavior. L1, a neuronal cell adhesion molecule, is associated with poor survival in malignant adult tumors. The aim of the current study was to determine expression of L1 in pediatric neuroblastoma.

Methods: L1 expression was assessed on a tissue microarray with 66 surgically resected neuroblastoma samples by immunohistochemistry with a monoclonal antibody and peroxidase method. Additionally, mRNA expression was analyzed by reverse transcriptase-polymerase chain reaction with L1-specific primers. Data were correlated survival data by log rank test and Cox regression multivariate analysis.

Results: L1 was detected in 57 (86%) of 66 neuroblastomas, whereas 9 (14%) were L1 negative. Median survival of all children was 72 months. Analysis with Kaplan-Meier method revealed a surprising and contrary finding to adult tumor entities: an association of L1 positivity with better event-free and overall survival (P < .001 and P < .01 by log rank test). Multivariate Cox regression analysis showed an independent prognostic impact of L1 negativity for event-free and overall survival of the children (P < .05).

Conclusions: In contrast to adult tumor entities, where L1 is associated with aggressive clinical behavior, our data show that L1 predicts good outcome in children with neuroblastoma. This novel finding suggests an inverse role of L1 in neuroblastoma. Future studies might focus on the molecular basis of the varying effect of L1 in different tumors.